Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
Optical disc drive systems are widely used for reading from and/or writing to an optical disc (e.g., a compact disc (CD disc), a digital versatile disc (DVD), a Blue Ray disc, etc.). An optical disc is generally placed on a turntable of an optical disc drive system, and the turntable rotates the optical disc while the optical disc is being read from or written to. A light beam, which passes through a lens of the optical disc drive system, generally performs a read or a write operation of the optical disc. If the optical disc is not placed perfectly concentrically with the turntable of the optical disc drive system, the optical disc may rotate (e.g., while a read and/or a write operation is performed) in an eccentric manner with respect to the turntable.
In a conventional optical disc drive system, an amplitude and a phase of an eccentricity of an optical disc may be estimated, for example, using a track error signal and a signal (e.g., a sum signal) from a diode detector in an optical pick up unit of the optical disc drive system. For example, the track error signal (e.g., which may be a sinusoidal signal) and the signal from the diode detector (e.g., which may be a cosine signal) are usually out of phase, and the phase difference between these two signals may be used to estimate a phase of the eccentricity of the optical disc. However, a modulation of the signal from the diode detector may be low, and the signal from the diode detector may be easily affected by, for example, scratches, birefringence or finger prints in the optical disc. Accordingly, estimating the phase of the eccentricity in the conventional optical disc drive system, using the track error signal and the signal from the diode detector, may be prone to errors.